.travis.yml in stateful_enum-0.2.1 vs .travis.yml in stateful_enum-0.3.0

@@ -1,4 +1,22 @@
 language: ruby
+
+cache:
+  - bundler
+
 rvm:
-  - 2.4.0
-before_install: gem install bundler -v 1.11.2
+  - 2.2.4
+  - 2.3.0
+  - ruby-head
+
+gemfile:
+  - gemfiles/Gemfile-rails.4.1.x
+  - gemfiles/Gemfile-rails.4.2.x
+  - gemfiles/Gemfile-rails.5.0.0.beta3
+
+before_install:
+ - sudo apt-get install graphviz
+ - gem install bundler -v 1.11.2
+
+matrix:
+  allow_failures:
+    - rvm: ruby-head